The technique disclosed herein relates to a physical quantity detection circuit used for a physical quantity sensor that detects a physical quantity given externally and to a physical quantity sensor device provided with the physical quantity detection circuit, and more particularly, to a technique of adjusting the phase relationship between a sensor signal and a detection signal.
Conventionally, physical quantity sensor devices capable of detecting a physical quantity (e.g., an angular velocity, an acceleration, etc.) are used in a variety of technical fields such as detection of shake of a digital camera, attitude control of a mobile unit (e.g., an aircraft, an automobile, a robot, a vessel, etc.), and guidance of a missile and a spacecraft.
In general, a physical quantity sensor device includes: a physical quantity sensor that outputs a sensor signal according to a physical quantity given externally; and a physical quantity detection circuit that detects a physical quantity signal (signal corresponding to the physical quantity) from the sensor signal using a detection signal (signal having a frequency corresponding to the frequency of the sensor signal). In such a physical quantity detection circuit, an unintentional phase shift may sometimes occur between the sensor signal and the detection signal due to fabrication variations (diffusion variations in resistances and capacitors, etc.) and fluctuations in the surrounding environment (e.g., changes in temperature, etc.). It is therefore important to adjust the phase relationship between the sensor signal and the detection signal to keep the sensor signal and the detection signal synchronized with each other.
To address the above problem, Japanese Patent Publication No. 8-14916 discloses a vibration gyro, provided with a phase correction circuit including a temperature-sensitive element (element having a predetermined temperature characteristic), to correct a phase shift caused by a temperature change.